title: Statistical optimization, interaction analysis and desorption studies for the azo dyes adsorption onto chitosan films.
abstract: Chitosan films (CF) were applied to remove azo dyes (tartrazine and amaranth) from aqueous solutions by adsorption. CF were prepared by casting technique and characterized. Response surface methodology was employed to optimize the adsorption process as a function of pH (2, 3 and 4) and CF concentration (100, 150 and 200 mg L(-1)). The possible interactions CF-dyes were investigated by Fourier transform infrared spectroscopy, dispersive energy X-ray spectroscopy, thermogravimetric analysis and color parameters. Adsorption-desorption cycles were also performed. The more appropriate conditions for the adsorption of both dyes were pH of 2 and CF concentration of 100 mg L(-1). Under these conditions, the tartrazine and amaranth adsorption capacities were 413.8 and 278.3 mg g(-1), respectively. The interactions between the CF protonated amino groups and anionic form of the dyes at pH 2 were confirmed. Desorption experiments showed that the CF can keep its adsorption capacity maximum for two cycles.
authors.affiliation: Unit Operation Laboratory, School of Chemistry and Food, Federal University of Rio Grande-FURG, 475 Engenheiro Alfredo Huch Street, 96203-900 Rio Grande, RS, Brazil. Electronic address: engtati@hotmail.com.
authors.forename: T V
authors.initials: TV
authors.lastname: Rêgo
authors.forename: T R S
authors.initials: TR
authors.lastname: Cadaval
authors.forename: G L
authors.initials: GL
authors.lastname: Dotto
authors.forename: L A A
authors.initials: LA
authors.lastname: Pinto
mesh_terms: D000327:Adsorption; D001391:Azo Compounds / Q000737:chemistry*; D048271:Chitosan / Q000737:chemistry*; D004396:Coloring Agents / Q000737:chemistry*; D008958:Models, Molecular
chemical_list: D001391:Azo Compounds; D004396:Coloring Agents; D048271:Chitosan
keywords: Adsorption; Amaranth; Chitosan films; Desorption; Tartrazine